Question: (a) Predict the values of m/zand the structures of the most abundant fragments you would observe in the mass spectrum of di-n-propyl-ether.

(b) Give logical fragmentations to account for the following ions observed in the mass spectrum of 2-methoxypentane: 102,87,71,59,31.

When high-energy electron hits an organic compound, it removes one of the electrons from the molecule and hence produces positively charged ions known as the molecular ions.

formation of molecular ion

The molecular ion is not only acting as a cation but also as a free radical because of the presence of an odd number of electrons. Hence, it can be called as enol radical cation.

The characteristic fragmentation of the molecular ion of a carbonyl compound (ketones and aldehydes) having at least one gamma hydrogen is known as the McLafferty rearrangement.

(a) For di-n-propyl-ether, m/z values of most abundant fragments are found to be at 73 and 43.

fragmentation equations of di-n-propyl-ether

(b)

fragmentation equations of 2-methoxypentane